Avalanche Forecast North Columbia

Monday 4th February 2019

Avalanche Danger Ratings Mon 4th Feb 4:43PM Danger Ratings Alpine: Considerable Danger Ratings Treeline: Considerable Danger Ratings Below Treeline: Considerable Persistent Slabs Persistent Slabs Wind Slabs Wind Slabs

Avalanche Canada Forecaster: kdevine

Date Issued:

Valid Until:

Natural avalanche activity has slowed down, but human triggered avalanches remain likely, especially in wind loaded areas and at lower elevations where a buried surface hoar layer has produced avalanches recently.

Confidence

Moderate -

Weather Forecast

MONDAY NIGHT - Clear periods / northwest winds 10-15 km/h / alpine low temperature near -17TUESDAY - A mix of sun and cloud / northeast winds 10-15 km/h / alpine high temperature near -15WEDNESDAY - Mainly sunny / northwest winds 15-25 km/h / alpine high temperature near -15THURSDAY - Cloudy with flurries, 5 cm / southwest winds, 15-35 km/h / alpine high temperature near -13

Avalanche Summary

Natural avalanche activity slowed to some degree on Sunday. Several natural avalanches to size 2.5 were reported. Human triggered avalanches to size 2.5 were also reported, many of these were triggered remotely (from a distance). Most of these failed on a persistent weak layer that was buried in mid January.Widespread avalanche activity was reported on Friday and Saturday. Numerous natural and explosives triggered avalanches to size 3.5, and human triggered avalanches to size 2 were reported. Many of these avalanches were triggered remotely (from a distance) and failed on the mid January layer.Human triggered avalanches failing on the mid January persistent weak layer have been reported almost daily for the past two weeks in the North Columbia region.

Snowpack Summary

30-80 cm of recent new snow sits on surface hoar (feathery crystals), facets (sugary snow), wind slabs and a crust on sun-exposed slopes. In many areas, recent winds have redistributed the new snow, forming wind slabs on all aspects due to shifting wind directions.A persistent weak layer that was buried in mid January is now buried 50-100 cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer has been most reactive at treeline and below, and was very reactive during the height of the recent storm.

Persistent Slabs Persistent Slabs

Likelihood

Likely - Possible

Expected Size

1.5 - 3

50-100 cm of snow is now sitting on a persistent weak layer of surface hoar and crust that was buried in mid January. This region has been the "hot spot" of activity on this layer, with more reactivity reported here than in neighboring regions.

Any steep opening in the trees should be treated as suspect right now.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

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Wind Slabs Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

30-80 cm of recent snow has been redistributed by recent winds in many areas, forming wind slabs on all aspects due to shifting wind directions.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

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